OJS 3.3.0.7 Comment by editorial board members in review discussions

Dear all,
we tried to add a discussion, but the team member was neither a reviewer nor the editor in charge. He got a message “##editor.discussion.errorAnonymousParticipants##” (which is not translated in German yet.
Is there an option to allow every team member to add new threads in a discussion of a review process? This is quite useful if the editor in charge is not present for a meeting.

For some reason sometimes I even cannot add a new thread if I add myself as an editor in charge.

Also is there a way to find all untranslated strings for a language? Then I would love to help finish the translations.
Best
Frank J.

grafik
I could narrow down the error.
If I select all of the reviewer and the editor here, I get the error message and the discussion thread is empty. If I drop one of them (uncheck the checkbox) it works fine.
Best
Frank J.

Did anyone already looked into that? @asmecher, maybe?
Best
Frank J.